For example, as for a pump for feeding oil stored in an underground tank to a private power generator, it is often installed on a ground surface (GL) close to the underground tank, in relation to a suction head of the pump, and generally no measure against submersion was taken. However, after the Great East Japan Earthquake, measures for preventing submersion of a pump have become considered to be important, and various pump submersion prevention measures are currently being studied and taken.
Heretofore, as a pump submersion prevention measure, there has been known a structure configured to install a pump in a watertight box or enclosure (watertight structural member), as disclosed in the following Patent Document 1. There has also been known a technique of using as a pump an oil-submersible pump and installing the pump under oil stored in an underground tank.
However, a pump submersion preventing structure using the watertight enclosure of the Patent Document 1 is based on completely covering a pump by the watertight enclosure. Thus, during use in a normal state, heat generated from the pump stays within the watertight enclosure, so the heat is likely to cause a malfunction or failure of the pump, particularly, when the pump is continuously used for a long period of time. Moreover, in the case where the pump is an oil feed pump, oil vapor stays within the watertight enclosure, and thus leads to a situation where explosion or the like is extremely highly likely to occur.
On the other hand, in the case of using an oil-submersible pump (water-submersible pump), the oil-submersible pump (water-submersible pump) is much more expensive than a commonly-used pump, and is required to take a considerable amount of cost, time and effort, specifically, required to be extracted from an inside of the underground tank during maintenance in the event of a malfunction or failure of the pump.
It is to be understood that such a submersion preventing measure is required for any device, such as an electric or electronic device and its peripherals (e.g., console), a mechanical device and a nuclear-related device, as well as a pump.